Validity of single vs. multiple FFQs in ranking nutrient intake among Japanese adults: the Tohoku Medical Megabank Project.

A single FFQ used for adults in the TMM cohort studies showed moderate validity. Estimates from multiple FFQs improved the accuracy slightly; nevertheless, this indicates that relying on a single FFQ is unlikely to result in a serious misclassifica-tion compared to using intake data from multiple FFQs over a relatively short period.